The present invention relates to a car head lamp auto-leveling system. The system automatically adjusts a tilt of an optical axis of a head lamp based on an inclination in the longitudinal direction of the vehicle (referred to as a xe2x80x9cpitch anglexe2x80x9d hereinafter) in the direction to cancel a corresponding variation in the pitch angle. More particularly, the auto-leveling system automatically adjusts the optical axis of the head lamp mainly based on the pitch angle of the standing vehicle.
The head lamp of this type has such a structure, for example, that the reflector into which the light source is inserted is fixed to the lamp body to be tilted from the horizontal tilting axis and also the optical axis of the reflector (head lamp) can be tilted from the horizontal tilting axis by the actuator.
The auto-leveling system in the prior art is constructed by providing a pitch angle detecting means, a speed sensor, a control portion for controlling the drive of the actuator based on detection signals supplied from them and the like, to the vehicle, and adjusts the head lamp such that the optical axis of the head lamp (reflector) is always set to a predetermined state to a road surface. 1However, conventional auto-leveling systems are constructed to execute the leveling in real time in response to the change in the vehicle posture due to the acceleration/deceleration during the running and the load change, such as loading/unloading of the baggage during the stop state, having people get in and out of the vehicle, and the like, regardless of the running and the stopped state of the vehicle. Therefore, the actuator is operated very frequently which increases the consumption of power, and also great durability is required of the constituent parts of the driving mechanism such as the motor, the gears, etc. which causes an increase in cost.
Therefore, for the purpose of providing the auto- leveling system that can be used inexpensively for the long term by reducing the frequency in the drive of an actuator, an auto-leveling system was proposed which controls the drive of the actuator at a predetermined interval (e.g., 10 second interval) during the stop state, and controls the drive of the actuator only once in running as far as the vehicle is in a stable running state (Patent Application Publication (KOKAI) 2000-85458). Since a plurality of changes in the posture of the vehicle during a stop can be collected in one drive control of the actuator, the durability of the actuator can be improved.
However, according to the above proposed auto- leveling system, even if the vehicle posture is changed immediately after the drive of the actuator (immediately after the leveling), the next drive of the actuator (leveling) is performed after 10 seconds lapsed and thus the driver feels the delay. Thus, since there is no relevancy between the timing at which the vehicle posture is changed by people getting in and out of the vehicle, the loading/unloading of the baggage, etc. and the timing at which the actuator is operated (10 second interval), such leveling arouses a peculiar feeling in the driver.
Also, the pitch angle data used in the drive control of the actuator are the average pitch angle data in the moving time of 1 second (1-second average pitch angle data), for example. Therefore, if the vehicle posture is changed very rarely in the middle of 1-second average, first the actuator is operated once by the 1-second average pitch angle data, on which the change up to the middle is reflected, and then the actuator is operated after 10 seconds by the 1-second average pitch angle data, on which the all changes of the vehicle posture are reflected, whereby the optical axis correction is completed. In this case, the actuator is operated (the leveling is executed) twice for one change in the vehicle posture, which leads to the reduction in the durability lifetime of the actuator.
The present invention has been made in light of the above problems in the prior art, and provides a car head lamp auto-leveling system which can be used inexpensively for a long term by reducing the frequency of the drive of actuators, and which does not arouse an unpleasant feeling in the driver.
A car head lamp auto-leveling system according to the invention includes head lamps whose optical axis are tilted vertically relative to a vehicle body by a drive of an actuator; a controlling means for controlling the drive of the actuators; a speed sensing means for sensing a speed of a vehicle; a pitch angle detecting means provided to at least one of left and right sides of at least one of a front wheel suspension and a rear wheel suspension, for detecting a pitch angle of the vehicle; and a memory portion for storing pitch angle data of the vehicle detected by the pitch angle detecting means; wherein the controlling means calculates moving average pitch angle data during a predetermined moving time based on the pitch angle detected by the pitch angle detecting means and then stores the data in the memory portion, and also controls the drive of the actuators based on the moving average pitch angle data such that optical axes of the head lamps are always brought into a predetermined tilted state with respect to a road surface when the vehicle is stopped or when moving, and
wherein the controlling means calculates the moving average pitch angle data during a plurality of different moving times based on the pitch angles detected by the pitch angle detecting means, respectively, and then stores the pitch angle data in the memory portion, discriminates stopped and moving states of the vehicle based on an output of the speed sensing means, controls the drive of the actuators in the stopped state based on the moving average pitch angle data during a stable vehicle posture wherein the stable vehicle posture is a state below a reference value that continues for at least a predetermined time and is maintained after the difference between respective moving average pitch angle data collected during a plurality of different moving times is increased once to exceed the reference value, and controls the drive of the actuators in the running state based on the moving average pitch angle data collected during a stable vehicle moving state wherein the stable vehicle moving state is a state which has a speed of more than a predetermined value and an acceleration of less than a second predetermined value and which moving state is continued and is maintained for a predetermined time.
In another implementation, a car head lamp auto-leveling system according to the invention includes head lamps whose optical axis are tilted vertically relative to a vehicle body by a drive of an actuator; a controlling means for controlling the drive of the actuators; a pitch angle detecting means provided to at least one of left and right sides of at least one of a front wheel suspension and a rear wheel suspension, for detecting a pitch angle of the vehicle; and a memory portion for storing pitch angle data of the vehicle detected by the pitch angle detecting means; wherein the controlling means calculates moving average pitch angle data during a predetermined moving time based on the pitch angle detected by the pitch angle detecting means and then stores the data in the memory portion, and also controls the drive of the actuators based on the moving average pitch angle data such that optical axes of the head lamps are always brought into a predetermined tilted state with respect to a road surface when the vehicle is stopped or when moving, and
wherein the controlling means calculates the moving average pitch angle data during a plurality of different moving times based on the pitch angles detected by the pitch angle detecting means, respectively, and then stores the pitch angle data in the memory portion, and controls the drive of the actuators in both stop and running states of the vehicle based on the moving average pitch angle data collected during a stable vehicle posture wherein the stable vehicle posture is that state wherein the moving average pitch angle is below a reference value and continues for at least a predetermined time and is maintained after the difference between the respective moving average pitch angle data during a plurality of different moving times is increased once to exceed the reference value.
The present invention is concerned with the leveling of a head lamp (optical axis correction) based on the pitch angle data of the vehicle in the stopped state. The pitch angle data collected during the stopped state of the vehicle are more precise than the pitch angle data collected during the moving state of the vehicle since they are less affected by disturbance factors at the time of detection. Since the drive of the actuators is controlled based on this precise pitch angle data, the precise auto-leveling can be carried out correspondingly.
Then, the control of the drive of the actuators in the stopped state of the vehicle is limited when the vehicle posture is stabilized after such vehicle posture is changed once, so that the frequency of operation of the actuators is small. Thus, the consumption of power can be conserved and the abrasion of the constituent members of the driving mechanism can be reduced. Also, since the actuators are operated (leveled) inasmuch as the changed vehicle posture has been stabilized, the disadvantage in the prior art is overcome because the actuators are not operated (leveled) twice for one change in the vehicle posture. In addition, since the actuators are operated (leveled) immediately when the changed vehicle posture is stabilized, a delayed operation feeling of the prior art is not aroused and also the driver senses no strange feeling.
Also, the leveling operation (optical axis correction) during the running state is limited to only during running, wherein the stable moving state has a speed of more than a predetermined value and has an acceleration of less than a second predetermined value and that continues for a predetermined time. In addition, the leveling (optical axis correction) that is performed based on the pitch angle data detected during an improper stop state of the vehicle, like the case where the vehicle is stopped on a sloping road, or the case where the vehicle is stopped but has ridden up on a sidewalk, or the like, can be corrected properly by the leveling (optical axis correction) that is performed based on the moving average pitch angle data (the data that are close to the pitch angle data collected in the stop of the vehicle) in this stable moving state.
In another implementation, the leveling (optical axis correction) during the running state is limited to only in the stable vehicle posture in which the vehicle posture is stabilized after such vehicle posture is changed, like the drive control (leveling) of the actuators during the stopped state of the vehicle. In addition, the leveling (optical axis correction) that is performed based on the pitch angle data detected during an improper stop state of the vehicle, like the case where the vehicle is stopped on a sloping road, or the case where the vehicle is stopped and has ridden up on the sidewalk, or the like, can be corrected properly by the leveling (optical axis correction) that is performed based on the moving average pitch angle data during this stable vehicle posture.
Also, if the predetermined stable running conditions are satisfied during the running state (during the stable running stage the state has a speed of more than a predetermined value and an acceleration of less than a second predetermined value that continues for a predetermined time), the drive control (leveling) of the actuators is executed. However, even if the predetermined stable running state conditions are satisfied during movement, sometimes the proper pitch angle data cannot be detected, like in the case of the vehicle turning, or slalom running, or movement on a rough road, etc. In other words, since the influence of turning forces and the influence of the unevenness of the road surface appears on the detected pitch angle data when the vehicle is turning, the slalom running, and the heavily rough road running, the pitch angle data that are clearly different from those in the stable running state such as the running in which no turning force is applied, the running on the smooth surface, etc. are detected. Thus, since the stable running conditions are satisfied in these running states which are normally rejected as the unstable running state, there is such a possibility that the leveling (optical axis correction) is performed based on the improper pitch angle data.
Therefore, since the drive control of the actuator (leveling) is executed only during the running state if the similar conditions to those in the stopped state of the vehicle (the state below the reference value is continued for the predetermined time after the difference between the moving average pitch angle data exceeds the reference value) are satisfied, the improper auto-leveling can be avoided without fail.
A feature of the car head lamp auto-leveling system according to the invention may be that a first drive control of the actuators by the controlling means which decides the stable vehicle posture when the difference between the plural moving average pitch angle data is smaller than the reference value continues at least for a predetermined time in disregard of a condition that the difference between the plural moving average pitch angle data in different moving times is increased once to exceed the reference value, and then controls the drive of the actuators based on the moving average pitch angle data collected during a stable vehicle posture state when the difference between the moving average pitch angle data in the stable vehicle posture and the pitch angle data used in preceding drive control of the actuators exceeds a predetermined value.
A characteristic of the vehicle suspension is that sometimes the suspension is not expanded and contracted when the static load applied to the vehicle during a stopped state is small. In this case, normally the change in the vehicle posture can be detected since the difference between the moving average pitch angle data exceeds the reference value because of people getting on and off during a stop. Nevertheless, a situation in which the change in the vehicle posture cannot be detected occurs since the suspension is not changed. Then, the suspension is restored to the stroke equivalent to the static load after the expansion and contraction of the suspension is repeated by the running of the vehicle, and as a result the vehicle posture is changed. But the vehicle posture is not changed (varied) during the stopped state after the running state but is changed during the running state. Accordingly, there is no situation to clear the condition that the difference between the moving average pitch angle data exceeds the reference value unless the new change of the vehicle posture is caused after the stop in which the vehicle posture is in the stable state. Thus, although the vehicle posture is changed in response to the small static load applied prior to movement, such change of the vehicle posture cannot be detected and thus there is the possibility that the leveling is not carried out. For this reason, in the case that the drive control of the actuator should be executed for the first time after the stop of the vehicle, the drive control of the actuator is executed to adjust the optical axis with regard to the above characteristic of the suspension if the deviation of the optical axis is detected, even in the situation that the difference between the moving average pitch angle data does not exceed the reference value (the change of the vehicle posture cannot be detected), whereby the irrationality due to the characteristic of the suspension can be overcome.
Also, the deviation of the optical axis is decided based on the difference between the pitch angle data at this time and the pitch angle data used in the preceding drive control of the actuator that exceeds a predetermined value. In this case, if the drive control of the actuator is executed as far as such difference exceeds the reference value that is more than the pitch angle equivalent to the hysteresis width of the actuator driving circuits of the right and left head lamps, the problem wherein only one head lamp is leveled can be avoided.
In this case, the pitch angle data used in the drive control of the actuators that is performed for the first time after the stop of the vehicle can also be utilized as the preceding control data, which is compared to detect the deviation of the optical axis in the drive control of the actuators that is performed thereafter in the vehicle stopped state.
Another feature of the car head lamp auto-leveling system may be that, in case a new vehicle posture stable state occurs, which is a state below the reference value that continues for at least a predetermined time and is brought about during operation of the actuators after the difference between a plurality of moving average pitch angle data exceeds the reference value, the controlling means controls the drive of the actuators based on the new moving average pitch angle data if the new moving average pitch angle data accelerates the drive of the actuators in a same direction. The controlling means controls the drive of the actuators based on the new moving average pitch angle data after the drive of the actuators in operation is completed if the new moving average pitch angle data returns the drive of the actuators in a reverse direction.
In the case that the actuator being driven is driven in the direction opposite to the current driving direction, such actuator is oppositely driven against an inertia force and thus damage may be caused to the actuator. Therefore, the actuator is driven (leveled) once to the target position corresponding to the current control amount (average pitch angle data), and then the actuator is driven to the position corresponding to the new control amount (average pitch angle data). But in the case that the actuator now being driven is driven further in the same direction as the current driving direction, if the target position is changed to the position corresponding to the new control amount (average pitch angle data), no trouble such as the damage of the actuator, etc. occurs. In addition, the corresponding total driving time of the actuator can be reduced and also the time required to adjust the optical axis can be shortened.
Another feature of the car head lamp auto-leveling system is that the drive of the actuators by the controlling means in the stable vehicle posture may be executed based on the moving average pitch angle data, that is picked up in a longest moving time, out of a plurality of moving average pitch angle data in a plurality of different moving times.
There are instantaneous disturbance factors such as the unevenness of the road surface during the running of the vehicle, the movement of the crew or passenger in the cabin in the stop of the vehicle, and the like. Since the moving average pitch angle data that has the longest moving time contains a large number of pitch angle data used in the averaging process, such data is less affected by such instantaneous disturbances and has high reliability. In contrast, the moving average pitch angle data derived from a short moving time is easily affected by such disturbances in contrast to the moving average pitch angle data derived from a long moving time, and is inferior in reliability as the control amount. Therefore, it is preferable that the moving average pitch angle data that has the longest moving time and is hardly influenced by disturbances should be used as the drive control data of the actuators.
Yet another feature of the car head lamp auto-leveling system according to the invention may be that the pitch angle data used in drive control of the actuators are two types of moving average pitch angle data that each have a different moving time, respectively.
The memory portion stores two types of moving average pitch angle data that have different moving times, respectively, and the controlling means simply calculates the difference between them and compares it with a reference value. Thus, configurations of the controlling means and the memory portion are simplified rather than the case where the moving average pitch angle data of three types or more are processed.
Embodiments of the present invention will be explained with reference to examples hereinafter.